What is Receiver Desensitisation?

Receiver desensitization occurs when an undesired signal from a nearby “off-frequency” transmitter is sufficiently close to a receiver’s operating frequency.  The signal may get through the RF selectivity of the receiver.  If this undesired signal is of sufficient amplitude, the performance of the receiver is degraded at its operating frequency.  The gain of the receiver is reduced, thereby reducing the performance of the receiver.

This is not attributable to any specific make or model of radio equipment.

On a typical truck shovel circuit radios operate through a repeater to enable emergency calls & site wide traffic to be heard. Subsequently radios have different transmit & receive frequencies & when a truck transmits in close proximity to another truck it can cause receiver desensitisation causing degradation of the received signal in the adjacent vehicle/s.

Methods to mitigate or rectify this problem include:

• Increasing signal levels in the area by using mobile (trailer) repeaters to supplement coverage from the main repeater towers
• Decrease mobile transmitter power levels
• Operate on a simplex frequency (a procedure to monitor the site wide channel such as a second radio in the shovel to inform the circuit of emergencies would need to be implemented.